Pin to pin laser signature circuit

Abstract

A laser signature circuit in a memory device comprises input pins for input signal into the memory device; internal circuits of the memory device connected to the input pins; a laser signature circuit connected between the internal circuits, wherein the laser signature circuit comprises a fuse to identify the memory device, the fuse is tested by input a signal into a first input pin of the input pins and the signal is measured on a second input pin of the input pins which is not necessary adjacent to the first input pin.

What is claimed is:  
     
       1. A method to determine a short of a laser signature circuit in a memory device, comprises: 
       inputting a voltage into a first input pin of said memory device; and  
       measuring a current on a second input pin of said memory device to determine said laser signature circuit whether or not is short and said memory device whether or not is repaired, wherein said laser signature circuit is connected between said first input pin and said second input pin.  
     
     
       2. The method according to claim  1 , wherein each of said first input pin and said second input pin is connected to at least one electrostatic-discharge (ESD) device for protecting electrostatic discharge from said input pins. 
     
     
       3. The method according to claim  2 , wherein said at least one electrostatic-discharge (ESD) device comprises a thin-gate electrostatic-discharge (ESD) device. 
     
     
       4. The method according to claim  1 , wherein each of said first input pin and said second input pin is connected to at least one clamping circuit for clamping noise input from said plurality of input pins. 
     
     
       5. The method according to claim  1 , wherein said laser signature circuit comprises at least one one-directional conducting device. 
     
     
       6. If The method according to claim  5 , wherein said at least one-directional conducting device comprises a diode. 
     
     
       7. A method for testing a fuse to identify a laser signature circuit in a memory device, wherein said laser signature circuit comprises a fuse coupled between two input pins of said memory device, comprising: 
       inputting a signal into an input pin of said input pins; and  
       measuring the signal on the other pin of said input pins.  
     
     
       8. The method according to claim  7 , wherein each of said input pins is connected to at least one electrostatic-discharge (ESD) device for protecting electrostatic discharge from said input pins. 
     
     
       9. The method according to claim  8 , wherein said at least one electrostatic-discharge (ESD) device comprises a thin-gate electrostatic-discharge (ESD) device. 
     
     
       10. The method according to claim  7 , wherein said laser signature circuit comprises at least one one-directional conducting device connected between said input pins and said fuse. 
     
     
       11. The method according to claim  10 , wherein said at least one-directional conducting device comprises a diode.